Brighton pushed Sheffield United closer to relegation as the Premier League's bottom club capitulated after Mason Holgate's dismissal in Sunday's 5-0 rout at Bramall Lane.
Holgate was sent off early in the first half for the United defender's ugly foul on Kaoru Mitoma.
Brighton made the most of Holgate's exit as Facundo Buonanotte and Danny Welbeck struck in quick succession.
Jack Robinson's second half own goal was followed by Simon Adingra's late brace, condemning the shambolic Blades to a sixth defeat in their last nine league games.
Chris Wilder's team are languishing seven points from safety with 13 games left to avoid an immediate return to the Championship.
United's 65 goals conceded in the Premier League this season are the most ever by a side in their first 25 matches in the competition.
A victory at fellow strugglers Luton last weekend had breathed new life into the Blades' hopes of avoiding relegation.
Yet they reverted to type with a self-inflicted loss that edged them nearer to the drop.
Brighton were winless in their last six Premier League away matches, but they had won 5-2 at Bramall Lane in the FA Cup fourth round in January and ended their barren stretch on their return to Yorkshire.
United threatened a goal inside two minutes when James McAtee picked out Jayden Bogle on the edge of the area and his drive was pushed away by Bart Verbruggen.
That proved a crucial moment as Brighton took control.
Wilder's men were reduced to 10 men in the 13th minute when Holgate's studs-up high challenge left Mitoma writhing in pain.
Holgate was initially booked but referee Stuart Attwell upgraded his decision to red card after using the pitchside monitor to review the on-loan Everton right-back's crude foul.
Brighton needed just seven minutes to make their numerical advantage count.
United complained that Brighton should not have been given as a corner because the ball appeared to come off Welbeck last.
From the controversial set-piece, Buonanotte made the Blades pay as he scrambled his effort over the line just before it was hacked clear.
Brighton struck again four minutes later, with former Manchester United forward Welbeck lashing high into the net from close-range after Wes Foderingham pushed Mitoma's shot into his path.
Wilder was left cursing his luck when Ben Osborn's close-range volley was ruled out by VAR for a tight offside call against the defender.
Roberto De Zerbi's side wrapped up their second league win of 2024 in the 75th minute when Robinson turned Mitoma's cross into his own net.
Adingra rubbed salt into United's wounds with a clinical volley from 10 yards in the 78th minute.
There was still time for Adingra's deflected effort to loop in over Foderingham in the 85th minute as United surrendered without a fight.
AFP